Christchurch Fluoridation Implementation Planning for a 40+ Facility System

Jack Deeley (Jacobs), Michele McDonald (Christchurch City Council), Silvia Vlad (Jacobs)

Following the promulgation of the Health (Fluoridation of Drinking Water) Amendment Act in 2021, water suppliers were encouraged to proactively commence fluoridation-related preparatory work on community supplies which service more than 500 people. Christchurch City Council provides drinking water to over 390,000 residents and is also responsible for the provision of safe drinking water to various small communities spread across Banks Peninsula. Because CCC does not treat water at most of its facilities beyond the addition of chlorine, the overall water supply system configuration is different from many large municipalities. This presents unique challenges when considering the fluoridation of drinking water.

CCC have undertaken the development of a comprehensive concept plan for the implementation of fluoridation at CCC public drinking water supplies, which encompass more than 40 pumping stations across the City and Banks Peninsula. Key factors and considerations established in the concept plan include the selection of fluoridation chemical and dosing method, integration with existing infrastructure including process equipment and controls, accessibility for operation and maintenance activities, operator health and safety and the standardisation of fluoridation equipment across the district. The key driver for this project was to get a clear and reliable understanding of the implications for CCC, specifically the capital investment required as well as operation and maintenance costs of implementing fluoridation.

Building on a preliminary system-wide implementation plan, conceptual designs were developed for five representative reference sites. The selected sites span a range of pumping capacities (1-11 ML/day), pumping configurations (artesian wells, well supplies with and without suction tanks, wells pumped to storage or directly into mains) and water quality characteristics (both ground and surface water supplies). Conceptual designs for two different chemical types were developed for a mid-sized facility, to consider the differentiators between application of two common fluoridation chemicals: sodium fluoride (solid) and hydrofluoric acid (liquid).

The five reference concepts have been used as the basis for the development of a staged implementation plan the over 40 facilities operated and maintained by CCC. This incorporates considerations for population served and potential benefits to the community, coordination with other capital projects and potential cross-over implications for ongoing chlorination optimization efforts. It also informs the CCC long term plan.

Using the CCC case study, this paper provides a review of considerations, potential pitfalls and key lessons learned for fluoride implementation, spanning chemical selection, layout development, controls integration and design standardisation. It presents a recommended approach for the implementation of fluoridation, highlighting the unique considerations needed for implementation at the scale of 45 facilities.